Linear reluctance motor

Abstract

A linear reluctance motor including a stator with a set of spaced blades each extending in the direction of the actuation axis, each blade including a plurality of alternating low permeability and high permeability teeth. A shuttle also includes a set of spaced blades each extending in the direction of the actuation axis interleaved with the blades of the stator, each blade of the shuttle also including a plurality of alternating low permeability and high permeability teeth. An active component is associated with either the stator, the shuttle, or both. The active component is divided into at least N phases, each phase including a set of blades, a flux return portion, and a coil wound to produce flux through the sets of interleaved blades in a direction substantially transverse to the actuation axis.

Description

RELATED APPLICATIONS[0001]This application claims priority from provisional application Ser. No. 60 / 431,604 filed Dec. 6, 2002.FIELD OF THE INVENTION[0002]This invention relates to a linear reluctance motor.BACKGROUND OF THE INVENTION[0003]Conventional electric motors, both rotary and linear, have very poor torque and force density. For heavy lifting applications, mechanical means such as gears and screws are more typically used. Fluidic devices including pneumatic and hydraulic systems are also used. These mechanical methods generally involve noise, wear, backlash, poor shock tolerance, and high reflected inertia. The fluidic methods tend to increase system complexity due to the addition of a fluid system. Fluid systems are also harder to control than electric systems. Due to seal wear, the fluid methods are unreliable and can contaminate sensitive environments when the working fluid leaks.[0004]A polyphase disc reluctance rotary motor is shown in U.S. Pat. No. 3,992,641 incorporat...

AI Technical Summary

Benefits of technology

[0010]The invention results from the realization that a better linear reluctance motor is effected by orienting the windings of the coils to produce flux through a set of interleaved blades of the stator and shuttle in a direction substantially transverse to the actuation axis. Also, by making the blades relatively thin, the blade density can be increased resulting in a large force density. The conventional wisdom is that each blade must be sufficiently thick and stiff to support itself and / or that the gaps between the blades must be large. The truth is that in a relatively slow moving motor, the blades can actually touch and rub against each other. With smaller gaps between the blades, there is less attractive force between the blades resulting less friction. And, the added benefit of reducing the extent of the gaps between the blades is reduced losses and less coil current required to generate the necessary flux.

[0027]In one particular embodiment, the active component is associated with the stator, the stator is attached to a structural tube, the blades of the shuttle connect to a structural beam, said beam is attached at the end to a tubular housing which is telescopingly connected to said structural tube, and said tubular housing is external to said structural tube. Alternatively, at least one phase is divided into at lease two magnetic circuits, each circuit having a coil, a flux-return a blade-set, said flux-returns being inwardly opposed so as to minimize leakage flux. In one example, the length of the interleaved portion of the stator and shuttle blades changes as the shuttle moves. In another example, the shuttle is relatively short and the stator long, the active component is associated with the stator, the phases are arranged serially along the axis of actuation, the blades of shuttle substantially overlaps at least three phases, and the stator has more phases than can be engaged by the shuttle at any given position.

Problems solved by technology

Also, by making the blades relatively thin, the blade density can be increased resulting in a large force density.

Images